In a number of fields, among them the field of sound or video recording, or motion picture photography, webs or elongated films are used on which to record the sound or images. In some applications of the sound, video, or motion picture films they are installed in cassettes in which a supply reel holds one end of the film or web rolled up on one side of the cassette, and a second reel on the other side of the cassette receives the other end of the web or film to be spooled up thereon as the first reel feeds the film or web to it. These prior art cassettes generally fully enclose the film or web and its reels so that, if additional web or film material must be added, or unwanted material removed, the top or bottom half of the cassette must be removed to gain access to the reeled up material. This is because such cassettes are fashioned in a clam-shell configuration.
There is always the danger of "spilling" the film web off the reel when attempting to add to the web or film, or delete material from it.
Many of the prior art cassettes are inaccessible for making editing changes by inserting or deleting portions of the web.
Some prior art separable cassette devices employ pairs of identical fully enclosed case-like devices each with a reel and the web or film running between them. They can be operated side by side. Others have two such assemblies interconnected with an enclosed slot to protect the film from light.
The reel to reel type of magnetic tape recorder for audio records has had a long history and was considered the state of the art until the advent of the audio cassette. The smaller size cassette with its convenience has become widely used.
As the technology of the smaller cassette advanced more uses were found in quality audio recording. They are used not only for music recording but also for teaching aids in, for example, language studies. A teacher may wish to modify a cassette audio tape to include specialized segments for particular students or classes. To do this with the conventional cassette requires disassembly of the cassette by separating the upper from the lower half, if they are at all disassemblable. The danger of spilling is constantly present since the spools or reels on which the webs or films are wound lie unprotected while the cassette is open.
One of the advantages in using reel-to-reel tape was in the ease with which it could be edited. An unwanted section could be removed and a new section inserted. Portions from one tape could be spliced conveniently on to another. Up to now the same covenience has not been experienced with the smaller cassette devices since the process most favored necessitated at least two recording machines to assemble material from different sources. It was necessary to copy the material from one cassette to another. This process results in quality deterioration with each successive re-recording. To splice-in tape sections in the prior art cassettes it was necessary to pull the web out of one of the head slots, cut the tape, and hope to make a good splice. Other techniques require the dissassembly of the cassette and the attendent danger of spilling the long web of tape because the reel spools are not supported when a conventional cassette is opened.